Chaging default email adress in From field in gmail

I am trying to set up an Android phone for my wife. She currently has a Gmail account that sucks in email from her Verizon Yahoo POP3 email account.

She sends all mail from here Verizon account through Gmail and the Apple Mail client. On the phone, the Gmail app defaults to sending from her gmail account with the dropdown allowing her select her Verizon account. Is there any way to force the Verizon account to come up as the default in the from field?